GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Jimmy - 2WD 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Diagnostic System Check - Lighting Systems

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

    2.

  2. This step determines if a Body Control Module (BCM) DTC based diagnostic path or a symptom based diagnostic path are to be followed.

    3.

  3. The presence of DTCs which begin with U indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

    4.

  4. This step determines if a total ECU failure exists or displays stored system related DTCs to be diagnosed.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the body control module.

Does the scan tool communicate with the body control module?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the body control module display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms

4

Does the scan tool display any DTCs which begin with a U ?

Go to Diagnostic Trouble Code (DTC) List in Data Link Communications

Go to Step 5

5

Does the scan tool display DTC B1397, B1398 or B1480?

Go to Diagnostic Trouble Code (DTC) List/Type in Body Control System

Go to Diagnostic Trouble Code (DTC) List/Type